1. Field of the Invention
The present invention relates to a proximity control method for transmitting a content and a network node using the proximity control method. More particularly, the present invention relates to a proximity control method which can perform improved Digital Rights management (DRM) by accurately measuring an end-to-end distance when transmitting a content, and a network node using the proximity control method.
2. Description of Related Art
Digital Rights Management (DRM) indicates a technology and a service capable of preventing an unauthorized utilization of digital contents and thereby protecting rights and benefits of a content provider. Specifically, DRM corresponds to a technology which can securely protect the content provider's rights and benefits, prevent an illegal copy, and also can support generation, distribution, and management of content, such as a fee charge, a payment as a proxy, and the like.
Also, DRM includes DRM technology which allows only an authorized user who has paid a fee to use content, software and security technology to authenticate and execute copyrights, payment technology, and the like. DRM was adopted by Napster, a music sharing service provider, for MP3 copyright protection in 2001. DRM has been appearing as a very important technology since online contents were provided for charge, and thus DRM was selected as one of ten future key information technologies by Massachusetts Institute of Technology.
FIG. 1 illustrates an example of a DRM technology in a home network according to a related art.
FIG. 1 illustrates devices 100 which are utilized in the home network, and a different copy prevention mechanism which is utilized in each of the devices. Specifically, the devices include different copy prevention mechanisms respectively, such as a Certificate Authority (CA) 101, a Digital Transmission Content Protection (DTCP) 102, a Content Protection for Removable Media (CPRM) 103, and a High-bandwidth Digital Copy Protection (HDCP) 104, and the like. Therefore, another configuration is required to help interaction between the different copy prevention mechanisms, and thus costs may be increased.
Suggestions using a round-trip time (RTT) mechanism have been made to solve the above-described problems of the DRM technology, however, the suggestions were insufficient and insecure for privacy and content protection.
For example, a DTCP of Internet Protocol (IP) is required to be limited to 7 milliseconds (ms) for an end-to-end latency time, and 3 hops for the RTT method. An electrical signal may travel at least 100 m/ms and thus a limit of 7 ms may generate an error after a distance of only hundreds of kilometers. Also, whether the hop limit is maintained may be known by a hop count, however, the hop count may not provide information concerning a substantial distance of a link between a server and a receiver. Specifically, an end-to-end distance may not be accurately measured in a network.
The above-described problems may occur in a home network using an Audio/Video Bridge (AVB). The AVB provides a streaming service with less latency in an Institute of Electrical and Electronics Engineers 802 (IEEE802) network using time-synchronization. Also, in the IEEE802 network, a mechanism to accurately measure an end-to-end distance does not exist and DRM of content, which is provided via the streaming service, may not be performed. Accordingly, there is a need for a proximity control method for transmitting content to devices within a selected distance.